(1) Field of the Invention
This invention relates to a heat pipe, in particular, a microchannel flat-plate heat pipe used for heat dissipation for a central processing unit (CPU) or other electronic integrated circuit (IC) chips.
(2) Brief Description of Related Art
The latest generation of Pentium IV CPU generates power more than 100 watts (Joule/sec). In order to maintain its normal performance and avoid overheating of the unit, more effective heat dissipating mechanism is needed. U.S. Pat. No. 5,880,524 discloses a heat pipe for spreading the heat generated by a semiconductor device as shown in FIG. 1. A cavity 105 is enclosed by a base metal 100 for a working liquid (not shown in the figure) to recycle. Heat sink fins 101 are arranged on the top of the base metal 100 for heat dissipation. Heat transfer medium 102 is under the base metal 100 to contact with a CPU.
A two-phase vaporizable liquid resides within the cavity 105 and serves as the working fluid (the coolant) for the heat pipe. A metal wick 103 is disposed on the inner walls to form a recycling loop within cavity 105 to facilitate the flow of the working fluid within the cavity. The working liquid in the cavity 105 flows in a direction as shown in arrows in FIG. 1. Firstly the working liquid is absorbed in the bottom portion of the wick 103. It evaporates when heat is transferred from the CPU and then condenses on the top portion of the wick 103. Heat is further transferred upward to the heat sink fins 101. The condensed liquid absorbed in the top portion of the wick 103 is then moved to the lower portion of the wick 103 due to capillary action of the wick 103.